Method of smelting mixtures containing magnetite directly into steel metals



v to make it profitable touse magnetite wholly,

Patented July 28, 1925.

PATENT;

BENJAMIN o. FORREST, or MERCHANTVILLE BoRouon, NEW-JERSEY, AssIGNoRon ONE-THIRD To a ARTHUR JONES AND ONE-THIRD To ennu -nu L. ROTH, BOTH or PHILADELPHIA. PENNSYLVANIA.

METHOD or sImLTING MIXTURES CDNTAINING MAGNETITE DIRECTLY INTo sTRnn METALS, I :1

I No Drawing.

To all whomi may concern:

Be it. known that I, BENJAMIN G, F o REs a' citizen of the United States of America, residing in the borough of Merchantville, county of Camden,'and State of New Jersey, have invented a Novel Method of Smelting Mixtures Containing Magnetite Directly into Steel Metals, of which the following is a specification.

v Where in the specification and claims I use the term steel metal, I mean to de-., scribe iron, or iron alloy produced in' a liquid condition, practically free from slag .and from graphitic carbon, and sufliciently refined to be either malleable when cast or capable of hardening greatly by sudden cooling, or both, according to the percent ages of carbon in the respective products of the various mixtures referred to in the context. When I use the term ore",. I

mean to describe not only a metallic com pound found in nature but also any con= centrate of such a compound made by, any means except smelting. Wherever I use the word magnetite, I wish'to be understood as meaning any form of magnetic oxide vof iron, including any mixture, of, ores, contain ing same, commonly called .black sands, derived from, alluvial, beachor glacial deposits irrespective of the association of oxidesof other metals with such oxide; of iron when found in p I nature or concentrated. NVhere I refer to the percentages ofdifierent materials in an mixture or elementsjin'any chargeor p'ro not, I mean percentages by weight unless Istate otherwise. By theexg' pression serviceable furnace;I mean any kind of containenothe'r than am ere crucible, suitable for smelting: mixtures. containing magnet-iteby means of heat applied directly to such mixtures, or generated therein, or

both, which can housed in the manner heremafter described.

My invention relates to the'direct producf tion of divers steel j metals from, various mixtures of magnetite with otherv suitable materials, by smelting such mixtures by the aid of manganese lores or oxides included in such materials. r I, 5 Th'e principal 0b ects of my Invention are or partly in the place of pig iron, wrought .parture from my proce'iss. I k e a e Furthermore, repeated tests have convinced, me, that theinitial and continual Application filed February 1, 1923. Serial 110. 616,403.

iron or scrap metalin making various kinds.

of steel and alloy steels and to use certain ores of other metals, instead of theirrespec tive ferro-alloys, in conjunction with mag-- net te 1Il producmg divers alloy, steels, which objects are obtainable'by the method of ores has been the largeamo unt of impurities contained therein andipurerores such as g it vbenlconsidered too refrac tory for ordinary use; Consequently it hasv been customary, in'making. steel metals, first toreduce iron, only partly purified, 'fronr the low grade ores which are commonly used. and then to refine it by someseparateprocess, and to add to it, while molten, all other, elements, including alloys, necessa forthe formation of steel or alloy stee 'of the:

desiredcomposition. Frequently magnetite has been used In IconJunctiOn with, hematite to 'bringup the yield of blast furnaces or;

as an addition to pig iron to fix the comb posit-ion of steel in open hearth furnaces. I However I have discovered, that .if sufiicient manganese, ore or I oxide of manganese i,

be first I mixed, a serviceable furnace hor flrl. f

crucible, with.a chargemompo sed' magnet te andvcarbonaceous matterand con-t taining nolow grade 'ore except such as may e needed 1 to introduce} desired! tluxing or 11 alloying materials therein, sothatthe quam tity, I of impurities present, which have a.

trQ nl n b i r i is elat ly. sm the mixture can smelted directly into steel metal with the, application of less heat than oxide :were not. initially present, without,

tion ofoneior more ferro-alloysorscrapsteel M to such charge, either when;mix ed or when .90 would be required-ii such manganese ore or molten. n'ay. beof advantage inl some' cases,

especially ,When making alloy steel, and'I'f us as y f;

do not consider any such presence in the charge of manganese ore of oxide accelerates the chemical reactions ocbut also after such reduction is practically completed so that then any oxide of manganese remaining assists in oxidizing the carbon remaining in the bath until the car bon content'thereof is approximately that desired in the steel metal being made, when the elimination of carbon may be checkedby casting or removing the charge or otherwise causing the temperature thereof to fall rapidly until the carbon no longer reduces any manganese, all the manganese meanwhile reducedassisting. to remove any undesired elements or compounds not previously removed, by'fluxing same into the slag or gases inthe same manner that it does when reduced from additions to molten metal in other processes.

My invention is practiced by first commingling, in convenient form, in any serviceable furnace or crucible, a charge chiefly comprising magnetite mixed with one or more substances containing elements, metallic or otherwise, needed or useful; in addition to the iron in suchmagnetite, for making any desired steel metal that can be made in a continuous operation at the temperatures attainable in the apparatus used, including always suflieient. carbonaceous matter to reduce and to" carcburize to the desired extent the metals to be smelted and to produce the heat necessary for smelting them, to the extent that it is to be generated from fuel within such container, with only a slight. excess of such carbonaceous matter beyond the amount required for all such purposes, calculated as closely as practicable, and some ore or oxide of manganese from which manganese can be reduced in quantity not'less than two per-cent of that of other metals to be smelted, if such manganese be not otherwise present in such mixture, and also any suitable flux or fluxes capable of removing any silica or other impurities also'contained in such charge butnot desired therein or admissible in such steel metaland by then heating such charge in such container bythe combustion of such fuel or other means to the temperatures required to reduce from such char e and to alloy the steel making elements t erein, say about 1,600 deg. centigrade, which temperatures will be attamed with less consumption of fuel or applied heat under such conditions than i such matter containingvmanganese were not present, on account of the exothermic heat of chemical reactions caused or accelerated b the oxides of such'manganese, including t e oxidation of carbon monoxide or removed from the container in a liquid nor of removing the latterbeing substantially like that practiced in the ordinary processes for making steel with containers and. apparatus similar to. those used for applying my process in any instance. The oxidation of excess carbon will be hastened by any-increase and retarded by a decrease of the temperature of the molten mass after reduction of the metals desired in the bath is completed.

The composition of the resulting product may be modified, if necessary or desirable, While molten, by the addition of one or more ferro-alloys thereto or by other means of obtaining definite roportions of constituents desired in a nal product not obtainable by the initial smelting operation. Either the initial or modified product may The carbonaceous matter, whether used only as a reducing and carbur izi'ng agentv or also as a fuel, may be introduced in one or more forms, either solid, liquid or gase-.

one, and as needed, aftersuflicient is put in the initial mixture to commence the reducing action, and likewise the other materials may be added in successivecharges so as ,to keep the furnace or other apparatus in constant operation as long as it remains in fit condition for continuous use providedv that such additions do not make it im-- practicable, considering the nature of the apparatus used, to oxidize the carbon in the molten metal in excess of the desired carbon content previous to the casting or removal of such metal or immediately thereafter while molten.

To insure the attainment of uniform results by my method, the conditions under which it is applied should be madeas favorable to its operation as possible. For instance, care should be taken to select the constituents of the charge so that the total mixture willnot contain more than one per cent by weight of either sulphur or phosphorus as my method affords no better means of eliminating those impurities than ordiv steel meta s by my process will be obvious.

out smelt-ing much cheaper condition, separately from the slag, the manbe cast into ingots for further treatment or otherwise shaped for industrial use.

Ill)

As black sands containing magnetite usually are roasted or sintered in preparation for smelting, the sulphur therein is almost completely removed by such preliminary treatment, and some of the other 1111- purities likewise.

My method may be practised by means of various types of apparatus in common use, including open hearth furnaces, but crucible and electric furnaces are more suitable than others for controlling the composition of the products of smelting" operations and expose the metals less than other furnaces to the absorption of sulphur from fuel and therefore are preferable for applying my process. Moreover, when the charge contains an ore more refractory than magnetite, 'it may be necessary to use an electric furnace to obtain the temperature necessary for the reduction of such ore, even though manganese oxide be present, but in all'cases the presence of manganese ore or oxide in the initial mixture serves to reduce the amount of external heat required to smelt it.

The proportion of the various ores or compounds to be employed will be readily determined according to the requirements or each case by those skilled in the art and will depend on the percentages of various elements present therein and reducible therefrom and the relative percentages desired, not exceeding the amounts feasible to incorporate, in the final product, and of avoiding any excess of impurities, especially any containing sulphur, phosphorus and silicon, beyond the amounts readily removable in the smelting operation, considering the nature of the apparatus and 0f the fluxes to be used, but it should be assumed and m r investigations have indicated that my met iod will notbe eilectiv'e on a commercial scale unless the charge to be smelted initially contains enough ore or oxide of manganese to contain manganese in quantity not less than .two per cent of the weight of other metal or metals to be reduced. Any manganese needed for alloying purposes may be introduced initially in like manner in addition to the amount specified as essential for applying my process but it must be understood that less than one-half of the quantity required in the initial charge for smelting purposes will be retained in the final product, because most of the manganese either in metallic or oxide form will combine with. impurities present and go off in the slag or gases. The quantity of magnetite expedient to use will depend upon the relative purity of the principal metallic materials mixed with it. It will be profitable to smelt magnetite in either large or small proportions with pig-iron, wrought iron, scrap or other refined metals, separately or in various combinations but When any ore other than magnetite is to be smelted therewith the latter should be suflicient to supply at least one-half as much metal as all the other ores in such mixture, so as tokeep down the percentage of gangue.

If the charge contains more than twenty per cent, of gangue, including silica, the

slag will be excessive and interfere with the purification of the metal and make it means are employed when the metal is molten to lower the manganese content which may also be done without any departure from my process.

I do not consider the use of an air blast or other oxidizing agents for any purpose at any stage of the operations any departure from my process although I have found it possible to dispense with same when using ore or oxide of manganese as stated, and

thus to avoid unnessary occlusion of oxygen and oxides in the products ofmy process.

My method is therefore distinguishable among other respects from-those hitherto used in makin steel from mixtures con taining magnetite in that my product may be produced entirely without the aid of any ordinary blast-furnace, Bessemer convert-er, additions of other ore or scrap as practiced in the open-hearth processes or methods of previously purifying-the materials used in the crucible process, or the hitherto practiced additions of term-manganese or ferrosilicon or recarburizers in any form to the molten metal during the final stages of production.

Obviously, the nature of the flux or fluxes to be used will depend on the character of the ingredients of the charge and practical steel-makers will know what the conditions in any given case require. I have found that it is generally necessary to form basic slags to remove silica and excesses of sulphur and phosphorus and that it is usually expedient to avoid using any furnace or crucible with an acid lining.

If the ores used in any case are so mixed as to be self-fluxiug. no other flux will be needed.

Any oxide of titanium mixed or associated with the magnetite in the charge, or added thereto, will operate as an efficient flux for silica and other impurities'that would otherwise combine with part of the manganese present either in metallic or oxide form.

Ill]

lfi)

Therefore by my process ores containing more than 3% of titanic acid may be utilized as an original source of iron in conjunction with magnetite for steel making without increasing the difliculties of smelting the materials used, if no appreciable amount of titanium is desired in the final product, but I have found it impossible to make any alloy steel containing more than 1% of titanium'out of mixtures of titaniferous ores with magnetite at any temperature below 1700 deg. centigrade although at higher temperatures I have made such 'steel by my process.

Of course, in every case, in addition to any requirements for "fuel, enough carbonaceous matter, whether in solid, liquid or gaseous form, must be used to suppl carbon or carbon monoxide in the quantity required to reduce all the desired metals and other elements from their ores or compounds and to carburize the iron to the extent desired which amount can be calculated within reasonable limits in all cases. \Vhon the amount of carbon required cannot be calculated closely, a small excess of carbon should be used and samples of the molten metal taken and tested to determine when the charge should be cast to obtain the desired product, or one approximating same.

If in any instance the metal becomes or remains too highly carburized, its decarburi- .zation can be hastened by addltlons merely of high grade magnetite practically free from su phur, phosphorus and silica without any departure from my process.

It will be manifest to those skilled in the art, after understanding my invention, that modifications and substitutions of equivaients may be. made in the materials to be mixed with magnetite for 'nalring steel metals by my method, such as the use initial; ly of manganiferous iron ore instead of a simple ore or oxide of manganese, without departing from the spirit or scope of my invention and that my invention is not to be limited to any particular kind of apparatus or mixture of materials except to the extent that enough magnetite, carbonaceous matter, (either solid, liquid or gaseous) within the limits indicated, ore or oxide containing manganese in quantity notless than the minimum specified as essential to keep ample oxides thereof in the charge and suitable fluxes be used, substantially in the manner -:lescribed, in any appropriate form of appsratus wherein any mixture containing said materials may be melted.

Furthermore, in conjunction with the steps already described, any means of ex peditiously, accurately or economically controlling, changing or fixing the carbon contents or hardening constituents or any component of any steel metal actually produced by my method of smelting mixtures containing magnetite may be employed without departing from the profitable use of such magnetite when mixed with some ore or oxide of manganese and, in some cases, with other ores or metalsalso, rather than the use of refined iron or refined iron and one or more ferro-alloys, as the chief material, in the production of any steel or alloy steels respectively and I do not mean to limit my invention to the use of my method only in connection with the processes of steel-making herein described.

Having now described my invention,

thereof and fluxes, substantially in the man ner described.

2. The metallurgical method, which consists of commingling magnetite, carbonaceous matter, some ore or oxide of manganese, and other suitable materials, including fluxes, needed for making steel metal of any special composition and smelting the same directly intosuch steel metal by means of suflicient heat,. carbon or carbon monoxide, and the aid of such manganese or oxides thereof and fluxes, substantially in the manner described.

3. The method ofmaking a steel metal of a desired and feasible composition, which comprisesdhe proper mixing of enough suitable I a materials, from which molten iron, free carbon, (or carbon monoxide), an oxide of manganese and any other element or elements useful in making such steel metal can be obtained in a single operation upon the application of suflicient heat to such mixture in a service able furnace or crucible, and smelting such mixture therein by means of such heat, carbon or carbon monoxide, and the aid of such manganese or oxides thereof and suitable fluxes, substantially in the manner described, and adding to the charge when molten any additional elements not initially present but required to make such steel metal or otherwise changingthe composition of the product of such smelting operation to attain the desired composition.

'4. The herein described method of smelting various mixtures of materials, including magnetite, carbonaceous matter, suitable fluxes and some ore or oxide of manganese, by means of suflicient heat, carbon or carbon monoxide, and the aid of such manganese or oxides thereof and fluxes, di-

Crl

including magnetite,

rectly into steel metals with compositions varying with the respective elements obtainable and. retained from the materials used in such mixtures respectively.

5. The hereindescribed method of accelerating the chemical reactions of smelting any mixture of materials, including magnetite and matter containing carbon, suitable for making any steel metal, which consists in initially using as part of such mixture some substance from which, when heated, enough oxides of manganese will be derived to increase. the exothermic reactions com mencedby the heat so applied sufficiently to make the heat of such reactions aid materially in the complete smelting of such mixture.

6. In the art of incorporating manganese into any steel metal, the step which consistsg, in first mixing some ore or oxide from which at least the amount of manganese desired in such steel metaland an excess equivalent in Wei ht to one percent of such metal can be rea ily reduced, with enough magnetite, carbonaceous matter and other materials needed or useful for making such steel metal, includin suitable fluxes, and then smelting such mixture by means of sufiicient heat, carbon or carbon monoxide, and the aid of such manganese or oxides thereof and fluxes and keeping the product molten until, by oxidation or otherwise, the manganese contents thereof is fixed at the percentage desired or changed to same, substantially in the manner described.

7. In the art of incorporating any 'element other than iron, carbon and manganese into any steel metal, the step which consists in first mixing some substance from which such additional element can be readily reduced, with enough magnetite, car'- .making such steel metal, including suitable fluxes, and then smelting such mixture by means of sufiicient heat, carbon or carbon monoxide, and the aid of such manganese or oxides thereof and fluxes and keeping the product molten until such additional element has been alloyed with the iron to the extent desired by fusion or the percentage of same in the product has been other-' Wise fixed, substantially in the manner described. 4

8. In the art of making steel metal containing any element or elements, in addi ti'on to carbon, alloyed with iron, the step which comprises the combination of such element or elements with such lron'or with such iron and carbon during the process of smelting such lron, or the chief part thereof, from magnetite or a mixture of materlals including-magnetite, by means of "sufficient heat, carbon or carbon monoxide, and the aid'of manganese or oxides-thereof and suitable fluxes contained in the initial smelting charge, substantially in the manner described. v p

In testimony whereof, I have signed my name to this specification, in the of two subscribing'witnesses.

BENJAMIN G. FORREST.

Witnesses:

Josnrxr L. STRIFE, MAHLON HUNSBERGER.

presence 

